Caster angle questions?

[King Nothing]

Is the flat spot on the bottom of the inner knuckle a good place to measure caster angle?

When you lift a Gladiator are you adding caster or removing caster?

I have caster correction brackets and measured 10 degrees of caster on the flat spot on the bottom of the inner knuckle.

If I move my upper control arms up will I be adding or removing caster?

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[GuzziMoto]

When you lift a solid axle vehicle it reduces caster. Then you add caster back via various options like geometry brackets or longer / adjustable lower front control arms. You can also use shorter / adjustable upper front control arms, but that is not the best way to add caster after a lift.

Measuring caster with an angle finder only works if you properly zero the gauge. If your zero is off, the final reading will be off. As to where to put the angle finder, I would think the best place would be on top of the upper ball joint. But again, that only reads right if you have an accurate zero or the vehicle is sitting 100% level.

What brackets and what set of holes in the brackets are you using? 10 degrees of caster is more than normal.

Making the upper arms shorter would add caster, making the upper arms longer would reduce caster. The opposite is true if you do the more conventional thing and adjust the lower arms, longer lower arms adds caster and shortening the lower arms reduces caster.
But you also need to be sure you have your lower arms in the right set of holes, assuming your geometry brackets have multiple sets of holes for the lower arms.

With geometry brackets and adjustable arms the baseline would be arms set to stock lengths and pick the right set of holes to get the correct caster. From there adjusting arms would only be to fine tune caster or centering the tire under the fender.

 

[King Nothing]

When you lift a solid axle vehicle it reduces caster. Then you add caster back via various options like geometry brackets or longer / adjustable lower front control arms. You can also use shorter / adjustable upper front control arms, but that is not the best way to add caster after a lift.

Measuring caster with an angle finder only works if you properly zero the gauge. If your zero is off, the final reading will be off. As to where to put the angle finder, I would think the best place would be on top of the upper ball joint. But again, that only reads right if you have an accurate zero or the vehicle is sitting 100% level.

What brackets and what set of holes in the brackets are you using? 10 degrees of caster is more than normal.

Making the upper arms shorter would add caster, making the upper arms longer would reduce caster. The opposite is true if you do the more conventional thing and adjust the lower arms, longer lower arms adds caster and shortening the lower arms reduces caster.
But you also need to be sure you have your lower arms in the right set of holes, assuming your geometry brackets have multiple sets of holes for the lower arms.

With geometry brackets and adjustable arms the baseline would be arms set to stock lengths and pick the right set of holes to get the correct caster. From there adjusting arms would only be to fine tune caster or centering the tire under the fender.

So my setup is 2 inch spacers in the rear and 2.5 inch Clayton coils up front that actually lifted me between 3.5-4 inches. Using the Rancho geometry brackets and my upper arms are currently in the bottom holes. Only one hole to choose from for the lowers

I measured the slope of my driveway at 3 degrees and got 13!degrees on the flat at the bottom of the inner knuckle giving me 10 degrees assuming that’s a good spot to measure.

will moving the upper arms up to one of the higher holes add or remove caster?

 

[VA6489]

Ideally you are looking for 7 degrees not 10.

 

[King Nothing]

Ideally you are looking for 7 degrees not 10.

I know 10 is excessive. I’m mostly trying to verify that I’m getting an accurate measurement where I’m measuring before I go trying to fix it

 

[Rusty PW]

Best thing to do is taking it to an alignment shop and get a print out of your alignment. This way you have something to go by

 

[bleda2002]

Is your pinion 4 degrees down? If not you are not at 10 degrees caster. I don't think any geo brackets are going to get you even close to 10 degrees if you got a real 3+ inches of lift so most likely the measurement itself is off here

 

[Gizmo]

I have never been able to get a consistent reading using the bottom of the inner Cs on any Jeep I have ever owned . I have not had a problem getting a consistent reading on the face of the pinion flange on the JT or on the face of the spreader holes on the sides of the diff cover.

 

[King Nothing]

I have never been able to get a consistent reading using the bottom of the inner Cs on any Jeep I have ever owned . I have not had a problem getting a consistent reading on the face of the pinion flange on the JT or on the face of the spreader holes on the sides of the diff cover.

Is the spreader hole face in line with the ball joints so it shows true caster or is there some math involved? How about the pinion flange?

 

[Gizmo]

Pinion flange

 

[VA6489]

I know 10 is excessive. I’m mostly trying to verify that I’m getting an accurate measurement where I’m measuring before I go trying to fix it

I have always used the upper Ball Joint as a measurment point. I also start with a level surface. I use a long level to check the floor for level and then use a angle finder to find the caster angle.

 

[GuzziMoto]

The bottom set of holes is for the most amount of lift. You probably need to be in the top set of holes, possibly the middle set of holes. But almost certainly not in the bottom set of holes.
Moving your control arms up to a higher hole will remove caster.

I would start with the arms in the top set of holes and see how that works out. If you need more caster at that point, I would try moving down to the middle set of holes. But honestly, I have never bothered measuring caster. You can feel how it drives, and if it has too little caster the steering will be nervous, twitchy, unstable even. Where as if it has too much caster the steering will be slow and heavy. But if you want to measure it, I would measure by the top of the ball joint. You have no way of knowing if that flat surface is square with the steering axis. Where as the top of the ball joint has to be square with the steering axis. The ball joints are what determines the steering axis.

 

[King Nothing]

The bottom set of holes is for the most amount of lift. You probably need to be in the top set of holes, possibly the middle set of holes. But almost certainly not in the bottom set of holes.
Moving your control arms up to a higher hole will remove caster.

I would start with the arms in the top set of holes and see how that works out. If you need more caster at that point, I would try moving down to the middle set of holes. But honestly, I have never bothered measuring caster. You can feel how it drives, and if it has too little caster the steering will be nervous, twitchy, unstable even. Where as if it has too much caster the steering will be slow and heavy. But if you want to measure it, I would measure by the top of the ball joint. You have no way of knowing if that flat surface is square with the steering axis. Where as the top of the ball joint has to be square with the steering axis. The ball joints are what determines the steering axis.

I’m definitely going to move the arms up to the top holes. I started with the bottoms because they were supposed to be for 4 inches of lift and I got almost 4 inches from the Clayton 2.5 coils. I’m fighting some terrible death wobble issues and I need to get the caster where it needs to be to rule that out before I move on. Really sucks because we’re fighting DW with both of our Jeeps right now so we don’t have a vehicle we can count on

 

[bleda2002]

Too much caster will cause heavy steering but not death wobble. Most likely something isn't torqued properly from doing the lift or another component isn't adjusted right. If after checking torque on every it still does real death wobble (as in you have to stop or almost stop to regain steering not just a shimmy) I'd recommend going to a good off road shop that can set this up rather than chase things.

 

[King Nothing]

Too much caster will cause heavy steering but not death wobble. Most likely something isn't torqued properly from doing the lift or another component isn't adjusted right. If after checking torque on every it still does real death wobble (as in you have to stop or almost stop to regain steering not just a shimmy) I'd recommend going to a good off road shop that can set this up rather than chase things.

Trust me, I know death wobble intimately. Been dealing with it on plenty of vehicles for over 30 years, starting with a 1975 F250 highboy. I’ve been through and checked torques. I’ll do it again but I still need to get the caster correct even if it doesnt help the DW. Google, however, does say that excessive caster can contribute to DW

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